Structural and vibrational properties of methane up to 71 GPa
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Authors
Bykov, M
Bykova, E
Martinez-Canales, M
Glazyrin, K
Smith, JS
Goncharov, AF
Publication Date
2021-11-08Journal Title
Physical Review B
ISSN
2469-9950
Publisher
American Physical Society (APS)
Type
Article
This Version
AM
Metadata
Show full item recordCitation
Bykov, M., Bykova, E., Pickard, C., Martinez-Canales, M., Glazyrin, K., Smith, J., & Goncharov, A. (2021). Structural and vibrational properties of methane up to 71 GPa. Physical Review B https://doi.org/10.1103/PhysRevB.104.184105
Abstract
Single-crystal synchrotron X-ray diffraction, Raman spectroscopy, and first principles calculations have been used to identify the structure of the high-pressure (HP) phase of molecular methane above 20 GPa up to 71 GPa. The structure of HP phase is trigonal R3, which can be represented as a distortion of the cubic phase B, previously documented at 7-15 GPa and confirmed here. The positions of hydrogen atoms in HP phase have been
obtained from first principles calculations. The molecules occupy four different crystallographic sites in phases B and eleven sites in the HP phase, which result in splitting of molecular stretching modes detected in Raman spectroscopy and assigned here based on a good agreement with the Raman spectra calculated from the first principles. Our study points out to a single HP phase unlike up to three HP phases proposed previously based on the Raman spectroscopy results only.
Sponsorship
Engineering and Physical Sciences Research Council (EP/P022596/1)
Identifiers
External DOI: https://doi.org/10.1103/PhysRevB.104.184105
This record's URL: https://www.repository.cam.ac.uk/handle/1810/330555
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